https://www.youtube.com/watch?v=XE4C-Pt4ioAthis link demonstrate and explain how the file must be decoded,an explanation can be:open the file with any nbtv player. run sodira or dream (software defined radio front end)when open select audio input speaker or stereo mix so the audio coming from the nbtv player simultaneously drive the sdr.tune the software at 12 kHz and a bandwidth of 4-5.5 kHz am double sideband ( 9-10 kHz rf bw) on sodira you can also demux stereo. its AM Motorola QAM Stereo.audio might content far 4- 5 kHz audible content but if you increase band width you might experience undesirable feedback.you can also play the file on windows media player. and let the sdr and the nbtv player hear from the stereo mix soudcard.you might need to setup audio inputs on recording devices.even you can edit the file, erase the video channel, up convert the file to 48000 kHz and play it directly on sdr software.but you must first apply an anti alias filter, otherwise you may obtain undesirable noises. I work on sony sound forge for editing and create those mux files

stéréo ! interestingbut this gave me an idea.Today we have 5.1 file format, wich can be used with computers and dvd/br players.Why not using 1 track for vidéo and 2 tracks for sound ( and others for alternate language or else )or even, having 3 video tracks, 30line, 32line, 60line, all in sync + the 2 remaining tracks for stereo sound